Currently, 4×4 and 6×4 drivelines, which are commonly used with semi-trailer trucks, incorporate a disconnect feature. The disconnect feature may also be useful in drivelines used with light motor vehicles such as pickup trucks or sport utility vehicles. The disconnect feature allows one drive axle to be disengaged from the driveline (and thus idled) to reduce friction losses and improve fuel economy during cruise conditions. When it is desired for the disconnected drive axle to be re-engaged with the driveline, a multi-plate wet friction clutch or a transmission type synchronizer is typically used to synchronize the idling auxiliary drive axle parts with the vehicle road speed. This wet clutch or synchronizer needs to be of a large enough capacity to transmit a drive torque to the auxiliary drive axle. Accordingly, such systems require a large capacity wet clutch or, alternately, a separate dog clutch due to the high torque level at the axle shaft in the drive torque mode. Further, the auxiliary drive axle typically utilizes an open wheel differential to avoid an added cost of a limited slip differential assembly.
It would be advantageous to develop a more cost effective system that can provide an axle shaft disconnect function, synchronizer function, a limited slip differential function, and an ability to transmit large amounts of torque in a compact and cost effective unit.